Potassium is a positively charged electrolyte or cation that is found mostly inside cells. A healthy kidney is essential to the body's ability to maintain normal potassium levels. Damage to the kidneys, adrenal disease, medications that cause decreased potassium excretion and tissue damage can cause high levels of potassium in the blood. Hyperkalemia is the medical term for high potassium. According to the "Merck Manual," high potassium is generally discovered when doctors order blood tests or an EKG for other reasons.
Bradycardia
According to the National Institutes of Health website MedlinePlus, high potassium can cause bradycardia. Bradycardia is the medical term for a slow heart rate. A normal resting heart rate is 70 to 80 beats per minute. Athletes may have a resting heart rate as low as 40 beats per minute. When bradycardia occurs, the cardiovascular system may have difficulty making minute-to-minute demands caused by changes in posture and activity. A person with bradycardia may be light-headed when going from low to high physical activity because the pulse rate does not increase sufficiently and blood pressure falls. A heart rate that is too slow means oxygen demands of tissues are not being met. Bradycardia may have no symptoms or be experienced as fatigue.
Heart Block
Potassium balance is an important determinant of how the heart's conduction system functions. Hyperkalemia can cause heart block, which is a disturbance of cardiac rhythm caused when the electrical impulse to stimulate the heartbeat is delayed or blocked altogether. According to the American Heart Association, heart block is classified according to the point of electrical stimulation the blockage occurs. Heart block can be first, second or third degree. The different types of heart block have distinct patterns on EKG.
Symptoms such as a nausea, weakness, weak or absent pulse, loss of consciousness or changes in breathing pattern are life-threatening signs of high potassium. Call 911 if any of these signs occur.
Ventricular Fibrillation
Hyperkalemia can cause ventricular fibrillation or "v-fib," which is an extremely dangerous and potentially fatal cardiac arrhythmia. The American Heart Association defines arrhythmia as "abnormal rhythm of the heart." Sustained ventricular fibrillation is not compatible with life. When ventricular fibrillation occurs, the heart is unable to pump sufficient blood to maintain circulation to the brain and other organs, and blood pressure falls to levels of shock.
Inability to supply the brain with sufficient blood flow causes sudden loss of consciousness. Sudden loss of blood flow to the brain can also cause stroke. Ventricular fibrillation is a medical emergency. With this or any other cause of sudden loss of consciousness, emergency medical support is essential. Prompt treatment of this dangerous arrhythmia can be life saving.
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